The above-referenced patent discloses novel methods of hydraulically sealing voids in bedrock or other natural or manmade materials. The present invention involves an extension of this methodology to sealing unconsolidated waste and other materials such as: waste incinerator ash, alkaline coal burning ash, unwanted hazardous mine tailings such as uranium ores, provided alkaline conditions can be maintained, entombing radioactive or other wastes, and the like. These and other applications are possible where the cessation or inhibition of generation of hazardous leachates from the presence or storage of these and other materials is desirable.
As mentioned in the previous patent, natural cementation of rocks and sediments in nature is a well known phenomenon. Under alkaline conditions (pH &gt;7.5), the most common natural cements by far are calcium or calcium/magnesium carbonates (mainly as calcite CaCO.sub.3). These natural carbonate cements occur by chemical precipitation or growth from the pore water or groundwater solution over time and reflect a physiochemical equilibration between mineral constituents of the sediment or bedrock and pore waters, connate waters, or ambient groundwaters.
A principal object of the previous patent was to provide methods by which to achieve artificially induced carbonate cementation at a rate sufficient for practical applications in creating hydraulically sealed strata in alkaline materials. The present invention extends these applications and further provides an alkaline buffer system for certain applications. This introduces an added control effect in terms of a capacity to continue a sealing action via cementation in the event of a future breach of seal developing, for example, by fracture upon settling of earth materials, or rupture consequent to seismicity.
While the previous invention included the potential of sealing materials other than earth strata, it is a principal object of this invention to apply the same scientific principles and similar methodology to sealing unconsolidated and other materials of man-made or natural origin, in appropriate circumstances at, above, or below the earth's surface.
More specifically, one of the principal objects is to provide a method of sealing waste incinerator ash to retard or inhibit leachate formation for the purposes of safe disposal in an alkaline landfill.
Another object is to provide a method of sealing alkaline coal electrical power (energy) plant waste ash in landfills in a manner very similar to that of the waste incinerator ash.
A further object is to provide a method of rendering radioactive wastes inert from the environment by entombing containers of the waste in a subterranian chamber surrounded by man-made or constructed alkaline buffer zone capable of producing artificially induced calcite, sealing the chamber wherein the containers are enclosed with an alkaline buffer zone to maintain alkaline conditions sufficient to induce calcite precipitation, and/or sealing the fractures in the bedrock immediately surrounding the chamber (provided a neutral or greater pH can be maintained) by induced calcite precipitation.
Still another object is to provide a method of sealing waste piles, etc. of mine tailings where alkaline conditions can be maintained over a substantial period of time. This would include, but is not limited to, the entombment of discarded, hazardous, uranium mine tailings or any other mine tailings where it is desirable to prevent the encroachment of hazardous leachate waters, derived from meteoric precipitation on the tailings, into the environment.
It is also an object of this invention to provide a compatible alkaline buffering method for certain applications to ensure long term stability of an existing or induced carbonate seal and/or provide a capacity for continued or future carbonate sealing action in the presence of leachate or groundwater, in the event of rupture or fracture after initial application.
Other objects will in part be obvious and will in part appear hereinafter.